Just use plain language and facts to show them the other side of the argument. 

Most of the NAA-based leases that I have seen have specific language about how long a guest can stay. 

In situations where the gas is separately metered I also recommend including language in the lease requiring tenants to provide a copy of their gas bill ever 3 months.  

Sign contracts requiring vendors to list you as additional insured with correctly worded indemnification language.

By setting clear screening criteria and using neutral language when communicating with applicants, you reduce the risk of legal issues and maintain professionalism.

I doubt you have to, despite the language in the letter you shared stating that “all LPs must participate.”

Maybe use LinkedIn, Instagram, Airbnb, etc to try to get in touch with them with ever escalating language.  

A typical cross collateralization may also be able to accomplish what you need, but I would not be using the 100% financing language as it indicated more risk than what you're actually looking for. 

Alternatively, target non-FHA buyers to avoid this issue altogether.Consult a Real Estate Attorney: Ensure your contract language is solid, especially with regard to title protection, seller obligations, and your rights in the event of default or dispute.By balancing your need for control with the costs of formal closing, you can structure a deal that works for both you and the seller while protecting your investment.4o

Speak to your attorney but the lease is most likely invalid because there was nothing exchanged. as mentioned i typically either get deposit and security at signing or have language in lease the lease is not valid until that term is met.I would send a lettter noting we have not heard from you and are canceling the agreement.